The 3.8 quake hit 4.3 miles northeast or Aguanga and 8.7 miles west-southwest of Anza at about 6:58 a.m.
The temblor came after four others in the same area, which were about two minutes apart. They were recorded as quakes with magnitudes of 3.1, 3.7, 3.1 and 2.5.
There were no immediate reports of damage or injuries.